Whenever work, such as rebuilding, repairs, and disassemblies of the internal combustion machine having a fuel injection system must be performed at a repair shop, the internal combustion engine, including the fuel injection system, must be separated from a fuel tank, and from a fuel supply system having at least one fuel line, before this type of work commences. In order to avoid the release of any fuel vapors and fuel, which may pose a health risk, the fuel storage of the fuel injection system must also be depressurized and drained when a tank injection (common rail) is present. In order to relieve pressure in the fuel storage, it is common, for example, to loosen the threaded connector attached thereto. This reduces the pressure inside of the fuel storage to atmospheric pressure, which, during the operation of the internal combustion engine—and even for a longer period of time afterward—is more than 100 bars. However, loosening the threaded connector has the disadvantage that usually fuel discharges uncontrollably into the environment, and may pose a health risk.
In addition to this method of relieving pressure and draining the fuel storage, other methods are also known, wherein the fuel from the fuel storage of the fuel injection system is drained into the fuel tank before disassembling the fuel line. DE 103 53 141 A1 discloses a method, wherein a piston in an unlit cylinder of the internal combustion engine is positioned so that compression pressure is built in the cylinder, which drains the fuel from the fuel storage of the fuel injection system into the fuel tank.
In many cases the internal combustion engine has already been separated from the fuel supply system due to previous working steps performed on the internal combustion engine. It is therefore the task of the invention of providing a method and a corresponding device, which ensures a safe and complete draining of the fuel storage, even in this situation.